In general, a knitting machine includes a number of yarn feeding apparatuses corresponding to the number of bobbins in order to feed each yarn as it is unwound from each bobbin to knitting needles within the interior of the knitting machine. An example of such a yarn feeding apparatus is disclosed in Korean Patent Publication No. 86-1053. Such apparatus has a storage drum equipped with a driving wheel driven by an endless tape. A number of conical surfaces are provided coaxially with each other at the upper and lower portions of a holder. Winding and unwinding is simultaneously executed to wind each yarn a predetermined number of turns around a storage drum.
In such an apparatus, the yarn arranged on the storage drum smoothly feeds yarn to the interior of the knitting machine. However, since an operator winds the yarn one-by-one on the storage drum to form each yarn loop, not only is the work cumbersome, but it also causes feeding tension differences in each yarn where the number of turns of yarn formed on each storage drum are different from each other.
In presently known and used yarn feeding apparatus, when abnormal tension is imparted to the yarn which is being unwound from the bobbin due to any defect in the bobbin itself, there is no mechanism capable of absorbing the increased tension. Therefore, the yarn will often break easily.
Further, when it is desired to change over from a positive type feeding to a free feeding to accommodate a switch in textile structure, generally, either a driving belt wound on the driving wheel is manually removed, or a locking device mounted on each driving wheel is handled one-by-one to allow the storage drum to be freely rotated. However, since these changeover processes are cumbersome and difficult to automate, there has been a problem that productivity is reduced.